Bosoz - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th March 2002, 08:07 AM   #1
ralf is offline ralf  Germany
diyAudio Member
 
Join Date: Dec 2001
Location: Germany
Question Bosoz

Where to place the volumecontrol ?

Has somone made experiences with placing the volumecontrol in Bosoz?

I ask me, if i should place it in the output?
Advantage: no ssssss hearable in the speaker, when the volume is down.

Or should it be better to be placeed in the input of Bosoz.



I will only use one pot (DACT) for volume controling, at the other places ( input or output) i will put one resistor, only (to save money)

Which solution sounds better?


Ralf
  Reply With Quote
Old 25th March 2002, 09:32 AM   #2
diyAudio Member
 
Join Date: Mar 2002
Location: Indonesia
Hi Ralf,

As far as I know, the smallest value of DACT pot is 10K, so it is probably you better put it on input of Bozoz.

Yamin
  Reply With Quote
Old 25th March 2002, 10:35 AM   #3
ralf is offline ralf  Germany
diyAudio Member
 
Join Date: Dec 2001
Location: Germany
Question why

why to the input?

can you explain me? Affects an volume control to the output the sound quality?

You should know: my speakers have a sensitivity at about 92db and when i put the volume control to the input of the bosoz the tweeters make a hearable "ssssssss".

How can i avoid this?

Please help me, cause a "ssssssss" has nothing to do with high end Quality.

Or should i build a different preamplifier? -but which one which converts unbalanced to balanced mode?
That would be a mess, cause the combination SOZ/BOSOZ sounds outstanding good.

Regards

Ralf
  Reply With Quote
Old 25th March 2002, 10:38 AM   #4
diyAudio Member
 
mefinnis's Avatar
 
Join Date: Feb 2001
Location: Adelaide, Australia
Actually, I think Nelson will suggest you put it in the output.

Ideally, the recommendation goes like this - adjust the input pot so the FETs are being driven adequately (output voltage swing 1-2V), then use the output pot as the volume contol.

Now, since you only want to use 1 pot (which I can understand entirely !!), I suggest you connect it initially in the input and adjust to a reasonable output level given your source (note, you will need to repeat this if you change sources). Measure the value and substitute fixed metal film resistors to match the circuit gain to your input source. Then place your DACT in the output, sit back and enjoy the music

cheers, mark
  Reply With Quote
Old 25th March 2002, 10:42 AM   #5
diyAudio Member
 
mefinnis's Avatar
 
Join Date: Feb 2001
Location: Adelaide, Australia
Addendum: Please note that when I say insert a metal film resistor, I actually mean 2 resistors as a voltage divider, this being equivalent to the pot ....... just in case I wasn't clear
  Reply With Quote
Old 25th March 2002, 11:58 AM   #6
diyAudio Member
 
Join Date: Mar 2002
Location: Indonesia
Yes, I agree with Mark. By the way, I just concern about the DACT impedance which is 10K ohm (Nelson suggested 5K ohm). High output impedance makes more difficult to drive the capacitance of long cable runs, which may in part be the reason of significant high frequency losses. Anyway, if you place it on the output make sure you have short cable to your amp.

Kind regard,
Yamin
  Reply With Quote
Old 25th March 2002, 12:59 PM   #7
ralf is offline ralf  Germany
diyAudio Member
 
Join Date: Dec 2001
Location: Germany
Default thank you

That`s it,

thanks to you all



Ralf
  Reply With Quote
Old 25th March 2002, 02:34 PM   #8
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Why not do the opposite. Insert fixed voltage divider at the output and DACT pot at the input. Since you might be concerned with the high impedance (10K) of DACT pot at the output the fixed voltage divider can be any impedance, preferably less than 500 ohm. In case you need more gain you can just use a switch or relay and remove it from the signal path.You might even use 2 or 3 different values and change it according to your needs. It only takes 2 or 3 extr resistors.
  Reply With Quote
Old 25th March 2002, 09:11 PM   #9
diyAudio Member
 
mefinnis's Avatar
 
Join Date: Feb 2001
Location: Adelaide, Australia
If you actually read Nelson's article, you will find he states:
Quote:
In general, the best performance occurs with the higher value of P5, giving 10 dB gain instead of 20 dB. If you don't need the gain, use 10 dB.

Adjusting the input signal level using P1 and P2 will allow you to optimize the operating point against the signal source level. The best performance occurs at approximately 1 or 2 volts output of the circuit (assuming P3 and P4 are turned up all the way). If you are running 10dB of gain, this means an input level of .3 to .6 volts, and if your source has much higher output, you can turn down P1 and P2 so as to set the input level to this region.

Once you have obtained the optimal gain and input level, adjusting the output level with P3 and P4 will give you an effective volume control which attenuates circuit noise as well as level. Of course you can use any of these pots as volume controls as you like.
Sort of answers all relevant questions really!

cheers, mark

PS: Remember the acronym, "RTFM", occasionally helps
  Reply With Quote
Old 25th March 2002, 10:37 PM   #10
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
My only concern was that 10K DACT pot at the output might be to high at some cases. If you look at the schematic of BOSOZ you notice that P4 is 5K.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
To BOSOZ or not to BOSOZ... please comment. spence Pass Labs 4 27th February 2012 02:57 AM
Poll! What do you use in your X-BOSOZ or BOSOZ for Volume Control and Input Selector? promitheus Pass Labs 87 19th February 2006 03:15 PM
X-bosoz vs. CCS X-bosoz, how does the sound compare? acliao Pass Labs 14 26th February 2004 12:55 AM
Bosoz lawbadman Pass Labs 5 14th July 2003 02:10 AM
10K Pot for the BOSOZ raincheck Pass Labs 13 20th September 2002 06:22 PM


New To Site? Need Help?

All times are GMT. The time now is 08:05 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2